Various types of defects exist on surfaces of a silicon-carbide wafer and an epitaxial wafer. Such defects increase a surface roughness of the silicon-carbide wafer, causing a bad influence upon the subsequent processes. A surface defect on the silicon-carbide wafer results in another defect in growing a single crystal layer and causes a rough surface. The surface defect on the epitaxial wafer may cause a partial isolation in laminating several layers. Further, when a device is fabricated using such a wafer, a leakage current may be increased by non-uniformity of metal electrode deposition and patterns.
For this reason, the life span of a device may be reduced and reliability of the device may be lowered. Thus, it is very important in manufacturing a high quality device to remove and control such a defect.